Eventually the 15-by-15-foot hatch will open and a crane will lower in weapons and sensors - and whatever other new technology defense researchers can dream up - to be launched from the "Virginia Payload Tube."

The payload tube is identical to the vertical missile launch tubes designed for new Virginia-class submarines. Beginning with the North Dakota, currently under construction, new Virginia-class boats will have two launch tubes, each with a diameter of about 7 feet, instead of 12 smaller ones that each can hold only a single Tomahawk cruise missile.

On submarines with the new, larger tubes, the Navy may eventually want to use Tomahawk missiles that can travel farther because they are bigger than the missiles used today. Or it may want to deploy unmanned aerial or undersea vehicles to collect data, sonar to look for mines, or equipment for several tasks, said Rear Adm. David M. Duryea, the warfare center's commander.

"Those are the things that are out there in the future," he said. "I think there will be a lot of excitement, a lot of innovation in that area as we go forward."

The Navy and Electric Boat are building the tube together. The Navy will test and develop new ways of using the tube at the NUWC lab before putting them on the Virginia-class attack submarines of the future.

Duryea said that after the payload tube is finished this summer he will invite businesses to the facility in Newport to measure it. They may think of new ideas for what could go in it, he added, and later, they could try out their innovations there.

"The Virginia Payload Tube significantly expands the types of payloads that can go onto submarines, and this test site will help us to incorporate sensors, weapons and other equipment that will be essential in the 21st century," said Kurt A. Hesch, EB's vice president for the Virginia program. "As a company with a long history of integrating payloads into submarines, we're looking forward to working with NUWC to provide the Navy what it needs to keep submarines as the ultimate multimission platform."

The tube is at NUWC, and not at EB, because NUWC already had a building for it, where all of the Navy departments and contractors could use it. And with the initial testing done inside a facility, it frees up a submarine that would otherwise have been needed.

"And everything that goes into the tube needs to be evaluated. That is our core area," Paul Melancon, the project lead at NUWC, said.

The building that houses the tube is called the Undersea Warfare complex, or launcher laboratory, because it is also home to several torpedo launchers being tested for surface ships and submarines. The roof was raised 30 feet so missiles and vehicles could be lowered into the tube. EB built the 50-ton tube at its Quonset Point facility and a giant crane lowered it through the roof and into the building in November.

The cost to construct the system, modify the building and pay for labor is $22 million, funded primarily through the Navy's Virginia-class program office.

Even as the Defense Department budget shrinks, Duryea said, the nation continues to invest in undersea warfare "quite a bit" to stay ahead of adversaries and ensure maritime trade routes remain open. The Navy awarded EB a record $17.6 billion contract on April 28 to build two attack submarines per year from fiscal 2014 to 2018.

"I think that says a lot about the value of the submarine force," Duryea said.

On Wednesday, employees from Electric Boat and NUWC installed piping for the tube.

Some of the EB employees involved in the project had been recalled to work on the North Dakota, said Mark Rodrigues, the department head for platform and payload integration development at the warfare center. The North Dakota's commissioning recently was postponed, according to the Navy, to allow for more time for additional design and certification work on the redesigned bow and to resolve material issues with vendor-supplied components.

The payload tube project is at least four to eight weeks behind schedule, Rodrigues said. But, he said, the plan is to finish the payload tube at the same time as the North Dakota goes to sea, so they have more time now that the commissioning is delayed.

Rodrigues said the warfare center's tube will also be used for training and for troubleshooting any issues once the North Dakota and its successors are out in the fleet.

"Those big tubes, by definition, support six Tomahawks. In the future, we have some 50 percent more volume, which can accommodate other future payloads beside Tomahawks," Rodrigues said. "That's the real strategic return on investment. It gives us the ability to explore the integration of those payloads. That is the big, future bang for the buck."

A ribbon cutting is tentatively planned for August. Duryea said the warfare center will have a "great facility to experiment," where what experiments they do will be determined by "people's imaginations."

j.mcdermott@theday.com

Pipefitters Dane Serra, left, Gary Turner, center, and welder George Turner, right, all of the Electric Boat Quonset Point facility, work on installing a valve system for the new "Virginia Payload Tube" that is being installed in the"launcher laboratory" at the Naval Undersea Warfare Center (NUWC) in Newport, R.I., Wednesday.

Project lead Paul Melancon talks about the "Virginia Payload Tube," left, while near the top of the scaffolding that surrounds the tube being installed in the "launcher laboratory" at the Naval Undersea Warfare Center in Newport, R.I.